Method and system for feeding a thread to a textile machine, at a constant tension and preset draw, as a function of the operating step of the latter

Abstract

A method for feeding a thread at a preset drawing to a textile machine includes a first feeder which sends the thread to the textile machine and a second feeder arranged spaced from the first feeder and which sends such thread to the latter, each feeder having a rotary member on which there is partly wound the thread before the feeding thereof and a speed sensor adapted to detect the rotational speed of such rotary member and a tension sensor to detect the tension of the thread exiting from each feeder. Controlling drawing the thread sent to the textile machine by controlling and adjusting the ratio between the rotational speed of the rotary member of the first feeder and the rotational speed of the rotary member of the second feeder.

The invention claimed is: 
     
       1. A method for feeding, with predefined drawing ratio, a thread to a textile machine, comprising
 first rotary means actuated by a first actuator thereof, 
 a first speed sensor detecting a first rotational speed of said first rotary means, and 
 a first tension sensor detecting a first tension of the thread, 
 wherein said first rotary means and said first speed sensor and the first tension sensor being arranged in proximity of the textile machine and cooperating with the thread before the thread reaches the textile machine, 
 second rotary means actuated by a second actuator thereof, 
 a second speed sensor detecting a second rotational speed of said second rotary means, and 
 a second tension sensor detecting a second tension of the thread, 
 wherein said second rotary means and said second speed sensor and the second tension sensor are arranged spaced from said first rotary means and said first speed sensor and said first tension sensor, 
 the second rotary means feeding the thread to said first rotary means and being more distant than the first rotary means from the textile machine, 
 said first and second rotary means and said first and second speed sensors and said first and second tension sensors being functionally connected to a control means, 
 said control means controlling the feeding of the thread to the textile machine, and said control means performing a measurement of the first rotational speed of the first rotary means, control of the second rotational speed of said second rotary means and definition of a drawing ratio of the thread sent to the textile machine based on the ratio between the first rotational speed and the second rotational speed, said drawing ratio being maintained equivalent to a predefined value acting on the second rotational speed of the second rotary means. 
 
     
     
       2. The method according to  claim 1 , wherein at least said first rotary means feed the thread to the textile machine at a constant tension, the constant tension being tension maintained equivalent to a preset value or setpoint value. 
     
     
       3. The method according to  claim 2 , wherein the preset value or setpoint value is, alternatively: a) fixed during the operation of the textile machine, or b) variable as a function of the state of progress of such operation. 
     
     
       4. The method according to  claim 1 , wherein said first rotary means, the first actuator, the first speed sensor and the first tension sensor are part of a first thread feeder and are associated to a body of the first thread feeder, the second rotary means, the second actuator, the second speed sensor and the second tension sensor are part of a second thread feeder and are associated to a body of the second thread feeder, each thread feeder comprising an electronic control thereof connected to the corresponding actuator and to the corresponding speed sensors and tension sensors, said electronic control being connected to the control means, said first and second rotary means being a pulley on which the thread is at least partly wound, the rotational speed of the pulley being controlled through the control of the rotational speed of the corresponding actuators, the rotational speed of the corresponding actuators being used for defining the drawing ratio. 
     
     
       5. The method according to  claim 4 , wherein the control means calculate a speed ratio of the actuators acting on the respective pulleys for defining the drawing ratio of the thread sent to the textile machine and, if such ratio is different from the predefined value, the control means intervene on the actuator of the second thread feeder to modify the rotational speed of the pulley thereof and make such ratio equivalent to the predefined value of the drawing ratio. 
     
     
       6. The method according to  claim 4 , wherein both thread feeders feed the thread at a constant tension, the tension applied to the thread by the first thread feeder being maintained constant at a value equivalent to a preset value, the tension applied to the thread by the second feeder being always maintained constant but equivalent to a value calculated to reach the predefined value of the drawing ratio. 
     
     
       7. The method according to  claim 4 , wherein the tension applied to the thread by the first feeder is alternatively: a) constant during the entire production cycle, or b) variable as a function of the state of progress of the operation of the textile machine. 
     
     
       8. The method according to  claim 5 , wherein the control means start calculating the drawing ratio and thus maintaining the drawing ratio constant and equivalent to a preset value upon detecting that the first thread feeder has passed from a stop step to a feeding step, that the textile machine has started demanding the thread to be processed and that the rotational speed of the pulley of the first thread feeder has become different from zero. 
     
     
       9. The method according to  claim 5 , wherein the second thread feeder feeds the thread at a constant speed, the feeding speed being maintained equivalent to a predefined setpoint, a speed modification of the actuator of the pulley of such second thread feeder being obtained by changing the setpoint value of the speed of the second thread feeder. 
     
     
       10. The method according to  claim 1 , wherein there is detected a state of operation of the textile machine and operative steps thereof, the drawing ratio being modified as a function of such operative-steps. 
     
     
       11. A system for feeding, with a predefined drawing ratio, a thread to a textile machine, said feeding occurring according to the method according to  claim 1 , said textile machine comprising
 first rotary means actuated by a first actuator thereof, 
 a first speed sensor adapted to detect a first rotational speed of said first rotary means and 
 a first tension sensor for detecting a first tension of the thread, 
 the first rotary means and the first speed sensor and the first tension sensor being arranged in proximity of the textile machine and for cooperating with the thread before the thread reaches the textile machine, 
 the second rotary means being actuated by a second actuator thereof and a second speed sensor adapted to detect a second rotational speed of said second rotary means and a second tension sensor for detecting a second tension of the thread, 
 the second rotary means, the second speed sensor, and the second tension sensor being arranged spaced from such first rotary means and first tension sensor and first speed sensor, 
 the second rotary means for feeding the thread to said first rotary means and being more distant than the first rotary means from the textile machine, 
 wherein the first and second rotary means and the first and second speed sensors and first and second tension sensors are connected to a control means for controlling the feeding of the thread to the textile machine adapted to control the drawing ratio of said thread, 
 the control means for performing the measurement of the rotational speed of the first rotary means, 
 the control of the rotational speed of the second rotary means and definition of a drawing ratio of the thread sent to the textile machine based on the ratio between the first rotational speed and the second rotational speed, said drawing ratio being maintained equivalent to a predefined value acting on the rotational speed of the second rotary means. 
 
     
     
       12. The system according to  claim 11 , wherein said first rotary means, said first speed sensor and said first tension sensor are part of a first thread feeder having an electronic control thereof connected to such first thread feeder, said second rotary means, said second speed sensor and said second tension sensor being part of a second thread feeder having an electronic control thereof connected to such second thread feeder, wherein the control means comprises a control unit, said thread feeders being connected to the control unit, said control unit being connected to the electronic controls of the first and second thread feeders and intervening on the second rotary means with the aim of controlling and commanding the speed thereof. 
     
     
       13. The system according to  claim 12 , wherein said control unit is connected to the thread feeders through corresponding serial lines. 
     
     
       14. The system according to  claim 12 , wherein at least the first thread feeder is a thread feeder at a constant tension. 
     
     
       15. The system according to  claim 12 , comprising one of the following characteristics:
 the drawing ratio varies as a function of various operating steps of the textile machine; 
 the predefined value is a constant and fixed value over the entire duration of the production cycle of the textile machine; 
 the second thread feeder is a constant tension feeder; or 
 the second thread feeder is a constant speed feeder. 
 
     
     
       16. The system according to  claim 12 , comprising one of the following characteristics:
 the control unit is part of one of the two thread feeders; 
 the control unit is integrated in the textile machine; 
 the control unit is remote connected, wireless, to the thread feeders and/or to the textile machine; 
 the control unit and the thread feeders are combined in a single device; or 
 at least one between the control unit and at least one thread feeder provides for a display and a keyboard. 
 
     
     
       17. The system according to  claim 12 , wherein said control unit is connected to the textile machine to detect at least the actuation thereof. 
     
     
       18. The system according to  claim 12 , wherein said control unit is connected to the start and the end of various operative steps thereof. 
     
     
       19. The system according to  claim 12 , wherein said control unit comprises a microprocessor. 
     
     
       20. A method comprising:
 feeding a thread to a textile machine at a predefined drawing ratio, the thread being fed to the textile machine through a first rotary means and a second rotary means; 
 detecting a first rotational speed of the first rotary means using a first speed sensor; 
 detecting a first tension of the thread using a first tension sensor; 
 detecting a second rotational speed of the second rotary means using a second speed sensor; 
 detecting a second tension of the thread using a second tension sensor; 
 wherein the first rotary means, the first speed sensor and the first tension sensor cooperate with the thread before the thread reaches the textile machine, and the first rotary means, the first speed sensor and the first tension sensor are spaced apart from the second rotary means, the second speed sensor and the second tension sensor; 
 wherein the second rotary means is more distant from the textile machine than is the first rotary means, the second rotary means feeding the thread to the first rotary means; and 
 wherein the first and second rotary means, the first and second speed sensors, and the first and second tension sensors are functionally connected to a control means; 
 controlling the feeding of the thread to the textile machine using the control means, the control means detecting the first rotational speed and the second rotational speed; and 
 controlling the second rotational speed and defining a drawing ratio using the control means, the drawing ratio being based on a ratio between the first rotational speed and the second rotational speed; 
 wherein the drawing ratio is maintained equivalent to the predefined drawing ratio.